Hearing the door close behind Xanthia, Pius stepped out into the main chamber. The dark shapes of the disgusting revellers loomed around him, filling the air with the stench of Chaos. His duty was clear.
Walking over to the door by which they had entered, he hit the light switch, turning back to face the room.
"I am Commissar Pius Valdemar, of the Imperial Guard. I have fought on a dozen warfronts to protect the people of the Imperium. I have seen friends and comrades die in the service of the Emperor. Scum like you would make their deaths worthless."
He levelled his pistol at the forehead of the first of the grotesque musicians.
"In the Emperor's name, I commit your souls to whatever daemons have claimed them."
Straightening his arm, he sighted and fired.
Spoiler
Show
Not sure if they're going to snap out of their haze or not - if they don't, Pius will execute them all systematically.
If they attack in response, here's a to-hit roll:
(1d100)[42]